package primary.others;

/**
 * @Author Elephas
 * @Date 2022/1/11
 **/
public class ReverseBits {
    public int reverseBits(int n){
        int ans = 0;
        for (int i = 0; i < 32; i++) {
            int temp = n&0x1;
            ans = ans | (temp << (32-i-1));
            n = n>>1;
        }
        return ans;
    }

    /*
        神奇的题解
     */

    private static final int M1 = 0x55555555; // 01010101010101010101010101010101
    private static final int M2 = 0x33333333; // 00110011001100110011001100110011
    private static final int M4 = 0x0f0f0f0f; // 00001111000011110000111100001111
    private static final int M8 = 0x00ff00ff; // 00000000111111110000000011111111

    public int reverseBits2(int n) {
        n = n >>> 1 & M1 | (n & M1) << 1;
        n = n >>> 2 & M2 | (n & M2) << 2;
        n = n >>> 4 & M4 | (n & M4) << 4;
        n = n >>> 8 & M8 | (n & M8) << 8;
        return n >>> 16 | n << 16;
    }

}
